Our objective is to study antecedents and sequelae of drug use among teenage students and young adults by analyzing a comprehensive, 13-year longitudinal data base collected from 2,500 subjects. Those subjects were in grades 5-10 when our study began in 1969. Between 1969 and 1976, measures were obtained regarding use of illicit drugs, alcohol, and cigarettes; attitudes toward and knowledge about drug use and drug users; attitudes toward cigarette smoking and cigarette smokers; personality; grade point average; school attendance; and school suspensions. Follow-up studies to be performed by mailed questionnaire during 1979-1981 will collect information regarding post high school substance use and significant life events. Topics covered will include current and past use of illicit drugs, alcohol, and cigarettes; education, work, and military experience since high school; social and family adjustment; health and hospitalizations; accidents; and contacts with the criminal justice system. More intensive studies will be performed on interview data to be collected from 600 subjects, selected from the sample of 2,500 to represet well-delineated subgroups defined by substance use and nonuse. Information will also be sought from the spouses or other intimate friends of those 600 selected subjects. The interviews will be conducted during 1980-1982.